1. Field of the Invention
The present invention relates to a high-frequency module to transmit and receive a plurality of communication signals with a common antenna.
2. Description of the Related Art
Various types of high-frequency modules for transmitting and receiving, with a common antenna, a plurality of communication signals using different frequency bands have recently been developed. For example, in a high-frequency module disclosed in Japanese Unexamined Patent Application Publication No. 2010-528498, a common terminal of a distributor is connected to an antenna, and a plurality of individual terminals of the distributor are individually connected to common terminals of switching elements. Individual terminals of each of the switching elements are individually connected to a transmission signal input circuit, a receiving signal output circuit, and a transceiver circuit.
High-frequency switch modules have also recently been developed in which the distributor is not provided and a switching element connects one of a transmission signal input circuit, a receiving signal output circuit, and a transceiver circuit to an antenna. The switching element in such a high-frequency switch module must have as many individual terminals as the number of transmission signal input circuits, receiving signal output circuits, and transceiver circuits. With an increasing number of communication signals to be processed, the number of individual terminals of the switching element must be increased.
Many multi-band power amplifiers capable of amplifying communication transmission signals using different frequency bands have recently been developed, and such a multi-band power amplifier is used for a high-frequency switch module. In a case in which such a multi-band power amplifier is used, it is necessary to individually input transmission signals amplified by the multi-band power amplifier into the above-described transmission signal input circuits.
FIG. 1 is a diagram illustrating a circuit configuration of a high-frequency switch module 10P in the related art that includes a multi-band power amplifier. An exemplary high-frequency switch module is illustrated that processes a GSM 850 transmission signal (approximately 900 MHz band), a GSM 1800 transmission signal (approximately 1.8 GHz to approximately 1.9 GHz band), a GSM 1900 transmission signal (approximately 1.9 GHz to approximately 2.0 GHz band), a WCDMA-Band 1 transmission signal (approximately 2.1 GHz band), and a WCDMA-Band 8 transmission signal (approximately 900 MHz band).
As illustrated in FIG. 1, the high-frequency switch module 10P in the related art includes a switching element 11 that includes a common terminal PIC0 connected to an antenna ANT and performs switching between transmission and receiving. In addition, the high-frequency switch module 10P includes a transmission signal switching element 30P between a multi-band power amplifier 40 and the switching element 11.
A common terminal PICt0 of the transmission signal switching element 30P is connected to the multi-band power amplifier 40. As a result, a transmission signal in a predetermined frequency band amplified by the multi-band power amplifier 40 is transmitted to individual terminals PIC11 to PIC14 of the switching element 11.
An individual terminal PICt1P of the transmission signal switching element 30P is connected to the individual terminal PIC11 of the first switching element 11 via a first low-pass filter 12. As a result, a GSM 850 transmission signal amplified by the multi-band power amplifier 40 is transmitted to the individual terminal PIC11 of the switching element 11.
An individual terminal PICt2P of the transmission signal switching element 30P is connected to the individual terminal PIC12 of the switching element 11 via a second low-pass filter 13. As a result, a GSM 1800 transmission signal and a GSM 1900 transmission signal amplified by the multi-band power amplifier 40 are transmitted to the individual terminal PIC12 of the switching element 11.
An individual terminal PICt3P of the transmission signal switching element 30P is connected to the individual terminal PIC13 of the switching element 11 via a SAW duplexer 14. As a result, a WCDMA-BAND 1 transmission signal amplified by the multi-band power amplifier 40 is transmitted to the individual terminal PIC13 of the switching element 11.
An individual terminal PICt4P of the transmission signal switching element 30P is connected to the individual terminal PIC14 of the switching element 11 via a SAW duplexer 15. As a result, a WCDMA-Band 8 transmission signal amplified by the multi-band power amplifier 40 is transmitted to the individual terminal PIC14 of the switching element 11.
As described above, in the high-frequency switch module 10P in the related art, in a case in which there are transmission signals that comply with different signal specifications and use frequency bands spaced apart from each other, a number of individual terminals equal to the number of transmission signals are required in the transmission signal switching element 30P. For example, in the case of the example illustrated in FIG. 1, although the GSM 1800 transmission signal and the GSM 1900 transmission signal that comply with the same signal specification and use frequency bands close to each other can be output from a single individual terminal, it is necessary to provide individual terminals for the other transmission signals. Accordingly, with an increasing number of communication signals (transmission signals), the number of individual terminals must be increased. This increase in the number of individual terminals leads to an increase in the size and cost of a switching element. As a result, the size and cost of a high-frequency switch module are also increased.